No, not the moderator. He's a big boy and does a fine job of that on his own...

I have a variety of salvaged transformers. I want to find if they are suitable for future projects. I'm using a variac to control line voltage. I'm doing this as a way to avoid any excitement (smoke) on my way to determining the secondary voltages.

The variac is rated @ 1.75 A and is fused. I had completed checking and recording voltages for several moderate sized transformers when I hooked up to one from a Peavey CS-800...a serious, large piece of iron...when I blew the fuse.

I have found 0.4 ohms on the primary & 0.3 ohms for each of the secondaries to CT. I find no shorts from windings to the case.

Is my variac too small for this large transformer?

If so, can I provide anything in-line to increase the protection or allow gathering measuremnents for large transformers?

Are you just flipping it on, or are you bringing up the test item from zero?

There can be a large starting surge powering up a transformer, but just sitting there with mains applied it should draw next to nothing. Is your fuse a slow-blow type then?

Due to the heavy gauge wire in that transformer, ohm readings won;t tell you much.

Look up "light bulb limiter" and make one and use it. My variac sits next to me at all times, but sometimes the simple trick is better. Especially for go vs. no-go.

And to detect shorted turns, go over the RG Keen's site New Page 1 and somewhere (in the tech tips, if I recall) is a VERY simple transformer tester you can make with a couple components. Make one of those real quick and use it too.